The IPCC report on climate change is the gold standard as it is the distilled result of thousands of the top climate scientists in the world. Its weakness is that it can only report what can be definitively proved at the time the report is written and also, the projections of the worst case scenario, RCP 8.5, are so bad that there is not much research to say what the result would be if it actually happened. There is a quote from Donald Rumsfeld explaining the reasons for invading Iraq without evidence which is more appropriate for the unpredictability of climate change. ‘There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know.’ I also like the quote from Mike Tyson.﻿ ’Everyone has a plan until they get punched in the mouth.’﻿ We are making big changes to our planet and even the last ten years have shown us that we are not prepared for the sudden changes that have happened. The Arctic ice was not supposed to melt for many years yet, and the big changes to the jet stream that have caused chaos in the USA, the UK, Germany, Russia and China were not forecast at the start of this century.Here are two areas that point to an uncertain future but I am sure that they are not the only ones.

CO2 emissions. This chart from the International Energy Agency overlays the real CO2 levels over the IPCC forecast scenarios from 2000.

The above chart from the International Energy Agency shows how CO2 emissions have always been at the top end of IPCC projections apart from during times of recession. The IPCC Fifth report shows an RCP8.5 scenario that probably reflects the reality of the political state of the world. In other words, ‘Business as usual’.

The above chart illustrates the problems. Most productive areas of the world are showing temperature increases of 4C to 6C at which level, food production as we know it cannot take place. The likely result will be substantial food shortages which in turn will precipitate civil unrest and war. Predicting war is impossible so it can be classed as an unpredictable tipping point. Sea level rise. Sea level rise has a lot of predictable components such as thermal expansion and the melt rate of ice for given temperatures. What cannot be calculated is the result of catastrophic collapse of an ice shelf or the sudden disintegration of land based glaciers in Greenland or West Antarctica. This dilemma is illustrated by the Real climate website appraisal of the IPCC Fifth repot.http://www.realclimate.org/index.php/archives/2013/10/sea-level-in-the-5th-ipcc-report/﻿Here are some extracts which are in turn includes extracts of the IPCC report. ‘The range up to 98 cm is the IPCC’s “likely” range, i.e. the risk of exceeding 98 cm is considered to be 17%, and IPCC adds in the SPM that “several tenths of a meter of sea level rise during the 21st century” could be added to this if a collapse of marine-based sectors of the Antarctic ice sheet is initiated. It is thus clear that a meter is not the upper limit’.﻿ - See more at: http://www.realclimate.org/index.php/archives/2013/10/sea-level-in-the-5th-ipcc-report/#sthash.ADBKTBhu.dpuf ‘In the latest assessment report of the IPCC we did not provide such an upper limit, but we allow the creative reader to construct it. The likely range of sea level rise in 2100 for the highest climate change scenario is 52 to 98 centimetres (20 to 38 inches.). However, the report notes that should sectors of the marine-based ice sheets of Antarctic collapse, sea level could rise by an additional several tenths of a meter during the 21st century. Thus, looking at the upper value of the likely range, you end up with an estimate for the upper limit between 1.2 meters and, say, 1.5 meters. That is the upper limit of global mean sea-level that coastal protection might need for the coming century’ See more at: http://www.realclimate.org/index.php/archives/2013/10/sea-level-in-the-5th-ipcc-report/#sthash.ADBKTBhu.dpuf﻿The world has experienced meltwater pulses in the past when the conditions have been right.﻿

Melt water pulse 1A showed an increase level of twenty meters in four hundred years, or four metres every one hundred years, or one metre every twenty years. With eleven of the world’s fifteen biggest cities at one metre above sea level plus big areas of productive farmland the economic consequences of sea level rise are incalculable. ‘Everyone has a plan until they get punched in the mouth’

The probability of an El Nino event in late northern summer has recently increased substantially and although this can bring drought to many critical regions it could deliver rain to California and break their drought. This poses and interesting question, California has had a persistent ridge of high pressure sitting over the Pacific, just off the coast, which has diverted rain clouds north to Alaska and high pressure systems are notoriously difficult to shift. This high pressure ridge, the cause of the drought, could be linked to the jet stream changes brought about by the diminishing Arctic sea ice. If the El Nino develops it would normally send rain bearing low pressure systems to California which would be very welcome even if it also delivers a few floods. Which one is going to win? Will the ridge of high pressure persist and divert the rain bearing systems north or will these systems overwhelm the high pressure and break the drought? Like most climate events it takes time for it to happen but the next year should be quite interesting.

NASA has observed an increase in the strength of the trade winds in the Pacific at the equator which is often a precursor to an El Nino event and they have raised the likelihood of it happening to 50%. El Nino events bring a flood of warm water across the Pacific from the Philippines area towards the Americas and this upsets the weather pattern over half of the globe bringing floods to some areas and drought to others. In a more stable La Nina situation trade winds blow from the Ecuador region of America out across the Pacific pulling up cool nutrient rich water from the deep and creating ideal fishing conditions. This can be clearly seen in the Weather Undergound temperature chart with a cool (yellow) area close to the South American coast.

The cool water spills out across the Pacific, warming as it goes.

Sea levels are not even around the World, like in a bath, but can pile up due to winds or thermal expansion from increased heat. This illustration is from a different period but shows what it would look like.

The NASA Jason2 satellite shows that the strong trade winds are piling up warm water in the Western Pacific.With the extra strong trade winds blowing, the warm water builds up and heats and this will continue for some months until the trade winds fade and the warm water spills back across the Pacific in a classic El Nino situation.

This chart shows where the heat is concentrated currently in the Pacific and the arrow indicates the approximate location of the Marshall Islands,

In a separate news item it was reported that the Marshall islands were flooded by extra high king tides. The Marshall Island in common with many other Pacific islands are very low lying and when you only have one metre of altitude for much of your living area a few extra centimetres can be critical between having dry feet or seeing your shoes float away.

This is not the first time these islands have flooded as the picture from 2012 shows but it does illustrate how little margin there is for safety. Sea level is currently rising at 3.16 mm a year globally http://climate.nasa.gov/ which to many of us is not much but if you only have 1000 mm total altitude a 500 mm sea-level rise would be critical ,then 31 mm every ten years is very serious and if you add to that extra strong trade winds to pile up the water and additional thermal expansion and you have a critical situation. This is only a precursor for the main event and we will have to find homes for many Pacific islanders in the years ahead.

People who have been watching the extreme weather in the Northern hemisphere might be wondering about the cause and if it might repeat itself. Drought in California, ice in Texas and floods in the UK, all at the same time and all record setting extremes . The cause is the loss of sea ice in the Arctic which is having an affect on the jet stream. A shortened explanation is here http://www.climateoutcome.kiwi.nz/ice-melt.html For a much more detailed explanation watch Jennifer Francis give her presentation. We are down to around four million square kilometres of ice compared with the original eleven million but if we get down to two million we will be in real trouble.